That is the thing about liberals and their whole theology. They do not believe in right and wrong. Their only moral guide is whether the action advances their agenda or not, and their agenda is so ambiguous (greater good for the greater number, sometime, somewhere) that they can justify any moral outrage, from mass rape to mass murder without a second thought.
Very true, but right is right, and wrong is wrong. Even a hopelessly indoctrinated leftist knows the difference, down deep inside. When they transgress against the basic morals they've fundamentally agreed with, it leaves a black mark of guilt on their heart that nothing except honest confession can ever wipe away.
I've heard it said that ex-Nazis are/were some of the most heartbroken people you could ever run across. Most (if not all) of them took an unimaginable weight of shame and guilt with them to their graves - whether they admitted it or not.